大肠杆菌代谢物组测定中抽提方法的比较分析

代谢物组学作为一种重要的功能基因组学工具,已经在微生物性状改良等方面得到了应用。实施代谢物组学研究需要定性和定量分析细胞内的全部代谢物。所以,必须有一种能够提供良好的重复性和相对抽提效率较高的细胞内代谢物抽提方法。本研究以特定厌氧条件下培养的大肠杆菌为研究对象,以电喷雾质谱直接进样测定为评价标准,比较并分析了冰甲醇、热乙醇和碱抽提3种抽提方法。结果显示,冰甲醇抽提的样品在电喷雾质谱实验中表现出良好的重复性和最高的峰强度,并能够同时检测到超过20种不同的胞内代谢物。     

Intramolecular vibrational dynamics of diacetylene and diacetylene-d1 via eigenstate-resolved overtone spectroscopy

The high resolution spectra of several CH overtone bands in diacetylene and diacetylene-d₁ were measured using optothermally detected excitation of a collimated molecular beam. The first overtone of the acetylenic CH stretches in these two molecules were recorded in a single resonance scheme using a 1.5 μm color center laser. The second overtone spectra were taken using sequential infrared/infrared double resonance with a 3.0 and a 1.5 μm color center lasers. The perturbations in the spectra have been analyzed to obtain information about the nature and timescales of the underlying intramolecular vibrational redistribution processes. The uncovered dynamical features appear to be dominated by anharmonic couplings and exhibit regular, not chaotic, behavior. The first and second overtone spectra of diacetylene-d₁ are consistent with a coupling model which involves coupling through a doorway state and then subsequent coupling to the bath. In diacetylene, a combination band was also recorded which, in the local mode picture, is equivalent to putting two quanta in one acetylenic CH stretch and one quanta at the other end of the molecule. Comparison of this spectrum with the spectrum obtained by putting three quanta in the same CH stretch, is consistent with earlier observations that delocalized combination bands are less perturbed than nearly isoenergetic pure overtone states.     

A velocity map ion-imaging study on ketene photodissociation at 208 and 213 nm: Rotational dependence of product angular anisotropy

Photodissociation dynamics of ketene following excitation at 208.59 and 213.24 nm have been investigated using the velocity map ion-imaging method. Both the angular distribution and translational energy distribution of the CO products at different rotational and vibrational states have been obtained. No significant difference in the translational energy distributions for different CO rotational state products has been observed at both excitation wavelengths. The anisotropy parameter beta is, however, noticeably different for different CO rotational state products at both excitation wavelengths. For lower rotational states of the CO product, beta is smaller than zero, while beta is larger than zero for CO at higher rotational states. The observed rotational dependence of angular anisotropy is interpreted as the dynamical influence of a peculiar conical intersection between the (1)B(1) excited state and (1)A(2) state along the C(S)-I coordinate.     

适合X′（G）=△的简单图的充分条件

文章通过对一类特殊的连通简单图的讨论得出一个适合的简单图的充分条件.     

Analysis of regulatory architectures in BST

Based on the data envelopment analysis (DEA) theory, the optimal pathway of metabolic reaction networks in biochemical systems is studied. After calculating the mixed-integer linear programming (MILP) model given by Bailey et al. twice, the decision making units (DMU) and the prediction model of DEA are constructed, where the inputs are levels of manipulated parameters (enzyme) and outputs are concentrations of metabolites. When the metabolic networks are reconstructed, the data are obtained by calculating MILP framework twice and the optimal levels of the manipulated parameter at different regular loops are predicted, thus simplifying the calculations of Bailey's.     

四价钼体系催化丁二烯聚合动力学

本文报导了MoCl₂(n-C₈H₁7O)₂-(i-Bu)₂AlOph体系催化丁二烯聚合动力学研究结果,得到聚合速率方程式R=k(C)_O(2)[M]=k_pa(c)_o(M),表观活化能18.6千卡/摩尔,指数前因子1.6×10¹⁰分^-1,以及不同温度下的催化剂利用率,活性中心浓度,活性中心平均寿命等,还证明了等聚合速率的聚合时间t_O与活性中心平均寿命相近。     

烯烃在Ag柱上顶替置换色谱机理的研究

选择环己烯、苯或甲基叔丁基醚（ＭＴＢＥ）作为高效液相色谱法（ＨＰＬＣ）流动相改性剂、正己烷为流动相时,吸附在银型磺酸键合硅胶固定相上的烯烃与流动相改性剂之间存在顶替置换作用,即烯烃的容量因子ｋ＇的对数与改性剂浓度［Ｂｍ］的对数间有很好的线性关系。由关联直线的斜率ｐ可获得烯烃置换改性剂的计量关系。但在不同流动相体系下,顶替置换过程不尽相同。在流动相改性剂浓度低于一定值时,内烯烃混合物与α－烯烃混合物都能与饱和烃分离并以不同的ｋ＇流出,各自ｌｇｋ＇值与ｌｇ［Ｂｍ］值之间也有线性关系。     

"金属的开发与利用"的教学设计

在实施化学新课程的今天,教学设计如何改变传统教育理念,依据化学课程标准创造性地使用教材和可利用的教学资源,恰当地选择教学方式和方法,有效提高学生科学素养已成为当前化学教育最有价值的问题.下面是笔者在2007年4月全国新课程培训中做公开教学的课堂教学设计,愿与各位同仁交流探讨.     

双功能有机小分子模拟酯酶研究

设计并合成了3个含有硫脲和咪唑基团的双功能有机小分子催化剂, 运用紫外光谱研究了它们对乙酸对硝基苯酯(PNPA)水解的催化活性. 考察了不同的pH条件下, 催化速率常数的变化情况. 发现与硫脲单功能催化剂相比, 双功能有机小分子催化剂具有更高的催化活性.     

大肠杆菌氧化还原辅因子代谢工程

NAD⁺、NADP⁺、NADH、NADPH等四类烟酰胺类辅因子也被称为氧化还原辅因子,是维持细胞氧化还原平衡,驱动胞内许多分解与合成反应的重要分子。近年来,辅因子在生物转化系统中的作用受到研究者的重视,氧化还原辅因子更成为人们关注的重点。文章综述了大肠杆菌（Escherichia coli, E. coli）氧化还原辅因子代谢工程研究的最新进展,重点总结最近发展的氧化还原辅因子代谢工程策略,讨论不同代谢工程策略对细胞氧化还原辅因子水平的影响及其在生物合成中的应用,并展望了辅因子代谢工程未来发展方向。